运行测试时，我看到以下错误：
Exception: java.lang.NoSuchMethodError: fs2.Stream$.bracket(Ljava/lang/Object;Lscala/Function1;Lscala/Function1;)Lfs2/internal/FreeC;
我首先确保通过explicitly declaring transitive dependencies并通过删除unused dependencies清除了生成文件，以生成以下build.sbt：
scalaVersion := "2.12.7"
organization := "com.example "
lazy val lambdas = (project in file("."))
.settings(
libraryDependencies += "org.typelevel" %% "cats-core" % "1.4.0",
libraryDependencies += "org.typelevel" %% "cats-effect" % "1.0.0",
libraryDependencies += "io.circe" %% "circe-core" % "0.10.0",
libraryDependencies += "io.circe" %% "circe-generic" % "0.10.0",
libraryDependencies += "io.circe" %% "circe-parser" % "0.10.0",
libraryDependencies += "io.circe" %% "circe-fs2" % "0.10.0",
libraryDependencies += "co.fs2" %% "fs2-core" % "1.0.0",
libraryDependencies += "co.fs2" %% "fs2-io" % "0.10.0",
libraryDependencies += "org.http4s" %% "http4s-circe" % "0.18.0",
libraryDependencies += "org.http4s" %% "http4s-client" % "0.18.0",
libraryDependencies += "org.http4s" %% "http4s-core" % "0.18.0",
libraryDependencies += "com.chuusai" %% "shapeless" % "2.3.3",
libraryDependencies += "com.amazonaws" % "aws-lambda-java-core" % "1.2.0",
libraryDependencies += "com.amazonaws" % "aws-java-sdk-core" % "1.11.422",
libraryDependencies += "com.amazonaws" % "aws-java-sdk-s3" % "1.11.422",
libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.5" % "test",
libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.0" % "test",
libraryDependencies += "io.findify" %% "s3mock" % "0.2.4" % "test"
)
一切都编译了，我的两个测试之一通过了。另一个由于上述错误而失败。这是被驱逐的sbt的输出：
[warn] Found version conflict(s) in library dependencies; some are suspected to be binary incompatible:
[warn] * co.fs2:fs2-core_2.12:1.0.0 is selected over 0.10.0
[warn] +- io.circe:circe-fs2_2.12:0.10.0 (depends on 1.0.0)
[warn] +- com.example:lambdas_2.12:0.1.0-SNAPSHOT (depends on 1.0.0)
[warn] +- co.fs2:fs2-scodec_2.12:0.10.0 (depends on 0.10.0)
[warn] +- org.http4s:jawn-fs2_2.12:0.12.0 (depends on 0.10.0)
[warn] +- co.fs2:fs2-io_2.12:0.10.0 (depends on 0.10.0)
[warn] * org.typelevel:cats-effect_2.12:1.0.0 is selected over 0.8
[warn] +- co.fs2:fs2-core_2.12:1.0.0 (depends on 1.0.0)
[warn] +- com.example:lambdas_2.12:0.1.0-SNAPSHOT (depends on 1.0.0)
[warn] +- org.http4s:http4s-core_2.12:0.18.0 (depends on 0.8)
[warn] * org.typelevel:cats-core_2.12:1.4.0 is selected over {1.0.1, 1.3.1}
[warn] +- io.circe:circe-core_2.12:0.10.0 () (depends on 1.4.0)
[warn] +- co.fs2:fs2-core_2.12:1.0.0 (depends on 1.4.0)
[warn] +- org.typelevel:cats-effect_2.12:1.0.0 (depends on 1.3.1)
[warn] +- com.example:lambdas_2.12:0.1.0-SNAPSHOT (depends on 1.3.1)
[warn] +- org.http4s:http4s-core_2.12:0.18.0 (depends on 1.0.1)
[warn] * io.circe:circe-jawn_2.12:0.10.0 is selected over 0.9.1
[warn] +- io.circe:circe-parser_2.12:0.10.0 () (depends on 0.10.0)
[warn] +- io.circe:circe-fs2_2.12:0.10.0 (depends on 0.10.0)
[warn] +- org.http4s:http4s-circe_2.12:0.18.0 (depends on 0.9.1)
[warn] * org.spire-math:jawn-parser_2.12:0.13.0 is selected over 0.11.0
[warn] +- io.circe:circe-jawn_2.12:0.10.0 () (depends on 0.13.0)
[warn] +- org.http4s:jawn-fs2_2.12:0.12.0 (depends on 0.11.0)
[warn] Run 'evicted' to see detailed eviction warnings
[info] Here are other depedency conflicts that were resolved:
[info] * commons-logging:commons-logging:1.1.3 is selected over 1.2
[info] +- com.amazonaws:aws-java-sdk-core:1.11.422 (depends on 1.1.3)
[info] +- org.apache.httpcomponents:httpclient:4.5.5 (depends on 1.2)
[success] Total time: 2 s, completed Nov 28, 2018 12:56:33 PM
使用sbt-dependency-graph似乎合法地需要两个版本的fs2-core：1.0.0和0.10.0。
这是我尝试使用sbt-assembly shading处理搬迁问题，方法是在需要它的http4s库中重命名旧版本的fs2。这个构建文件实际上什么都没有编译，所以我猜我的设置方式存在多个问题。
//build properties
//sbt.version=1.1.2
//assembly.sbt
//addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.8")
scalaVersion := "2.12.7"
organization := "com.example"
lazy val fatJar = project
.enablePlugins(AssemblyPlugin)
.settings(
libraryDependencies ++= Seq(
"org.typelevel" %% "cats-core" % "1.4.0",
"org.typelevel" %% "cats-effect" % "1.0.0",
"io.circe" %% "circe-core" % "0.10.0",
"io.circe" %% "circe-generic" % "0.10.0",
"io.circe" %% "circe-parser" % "0.10.0",
"io.circe" %% "circe-fs2" % "0.10.0",
"co.fs2" %% "fs2-core" % "1.0.0",
"co.fs2" %% "fs2-io" % "0.10.0",
"org.http4s" %% "http4s-circe" % "0.18.0",
"org.http4s" %% "http4s-client" % "0.18.0",
"org.http4s" %% "http4s-core" % "0.18.0",
"com.chuusai" %% "shapeless" % "2.3.3",
"com.amazonaws" % "aws-lambda-java-core" % "1.2.0",
"com.amazonaws" % "aws-java-sdk-core" % "1.11.422",
"com.amazonaws" % "aws-java-sdk-s3" % "1.11.422",
"org.scalatest" %% "scalatest" % "3.0.5" % "test",
"org.scalacheck" %% "scalacheck" % "1.14.0" % "test",
"io.findify" %% "s3mock" % "0.2.4" % "test"),
assemblyShadeRules in assembly ++= Seq(
ShadeRule.rename("co.fs2.**" -> "old_fs2.@1")
.inLibrary("org.http4s" %% "http4s-circe" % "0.18.0")
.inLibrary("org.http4s" %% "http4s-core" % "0.18.0")
)
)
lazy val kraken_shaded = (project in file("."))
.settings(
name := "kraken-shaded",
packageBin in Compile := (assembly in (fatJar, Compile)).value
答案 0 :(得分：1)
我不是 http4s 和 fs2 的专家，但我认为 fs2 的1.0.x版本引入了重大变化。
而且，如您所见here， http4s 0.18.x是针对 fs2 0.10.x构建的。
因此，我不认为您可以使它们一起工作。
您可能会想将 fs2 的0.10.x版本着色为 http4s ，并在项目中使用1.0.x版本...
但是，我什至认为这是不可能的，除非您从未使用过由 http4s 创建的 Stream ，也没有将 Stream 传递给 http4s -绝对不是它的工作方式。
不过，您可以使用http4s 0.20.x。
现在，它是一个里程碑，因此您可以期望更改会变得稳定-但是，如果您不想降级到 fs2 {{ 1}}。